潮控河口湾环境下的沉积相特征研究——以D-F油田M1油藏为例

Study on Characterisrics of Sedimentary Facies Formed under Tide-dominated Estuary Environment: Taking M1 Reservoir in D-F Oilfield as an Example

综合利用岩心、测井及地震资料,对T区块D-F油田M1油藏进行了层序划分,并建立等时层序地层对比格架,认为M1层为1个四级层序,可划分为M1-Zone、M1SS-1、M1SS-2和M1SS-3共4个五级旋回。在层序划分的基础上,根据岩心中的潮汐韵律层理、交错层理等沉积构造特征及构造演化、生物遗迹等证据,对研究区沉积相类型及特征、沉积相平面及纵向展布特征和沉积相演化模式进行研究。结果表明,地区整体为海侵体系域,沉积相类型为潮控河口湾沉积和陆棚相沉积,潮控河口湾沉积主要发育在M1SS-1、M1SS-2和M1SS-3旋回,微相类型主要有潮汐砂坝沉积、潮汐砂坪沉积、混合坪沉积及潮汐水道沉积等。陆棚相沉积发育在M1-Zone旋回,微相类型包括陆棚砂沉积和陆棚泥沉积。进一步分析沉积相展布和沉积环境特点,推断其沉积模式为河流相和潮控河口湾相—完整的潮控河口湾相—潮控河口湾相和小规模的陆棚相—发育含海绿石砂岩和泥岩的陆棚相。

By synthetically utilizing core,well logging and seism data,the sequence of M1 reservoir of D-F oilfield is identified and divided,and then the isochronous sequence stratigraphic framework of the M1 reservoir is established. It is held that M1 reservoir is a fourth-order sequence,the fourth-order sequence can be divided into 4 fifth-order cycles,and they are named as M1-Zone,M1SS-1,M1SS-2 and M1SS-3. Based on the division of sequence,the type and characteristics,the plane and vertical distribution characteristics and the evolution mode of the sedimentary facies in the study area were studied according to the tidal rhythmic bedding and cross bedding in cores,tectonic evolution,lebensspur,and so on. It is shown that,the study area is a transgressive systems tract,the sedimentary facies includes tide-dominated estuary facies and shelf facies. The tide-dominated estuary deposit mainly develops M1SS-1,M1SS-2 and M1SS-3 cycles,and its sedimentary microfacies mainly includes tidal sand bar,tidal sand flat,mixed flat and tidal channel. The shelf deposit mainly develops M1-Zone cycle,and its sedimentary microfacies mainly includes shelf sand and shelf mud. Through the analysis of sedimentary facies distribution and sedimentary environment,it is deduced that the sedimentary mode of M1 reservoir is ＂ fluvial facies and tide-dominated estuary facies-complete tide-dominated estuary facies-tide-dominated estuary facies and small-sized shelf faciesshelf facies with glauconite sandstone and mudstone＂.